Single piston, cam driven high pressure pumps have become a common solution for generating high pressure fuel in today's common rail, direct injection, gasoline engines. These pumps are typically driven via a tappet and cam with multiple lobes. In order to keep the tappet in contact with the cam and pump piston in contact with the tappet at high speeds, a coil spring is positioned between the pump body and a spring seat affixed to the pump piston. This execution has proven robust in regions of the world with well controlled fuel quality. In regions of the world with poor fuel quality, pump piston seizures have been a problem due to fluid film breakdown and poor lubricating qualities of those fuels. It is advantageous for these applications to reduce pump piston side loads in order to minimize the fluid film breakdown. One significant source of these side loads is the out-of-squareness of the piston/tappet return spring positioned between the pump body and plunger spring seats. When both ends are constrained by each spring seat to radially align the spring, the spring must be deflected to do so, and in the installed state a significant side load will be imparted to the pump piston.